[Trade-off and synergistic relationship of land use function and zoning in coastal saline-alkali area: A case study of Huanghua, Hebei, China].

Analyzing the multi-functional evolution of land use can help solve the confusion in the relationship between land use functions and unreasonable land use structure. From the perspective of ecological security, we integrated multi-source data on the basis of quantitative evaluation of various land use functions, and used the method of combining band set statistical model and bivariate local Moran's I to measure the dynamics of trade-off and synergy relationship between land use functions in Huanghua, Hebei from 2000 to 2018, and divided land use functional areas. The results showed that production function (PF) and life function (LF) showed the alternate evolution of the trade-off and synergy relationship, which mostly occured in the central urban areas such as the southern region. The PF and ecological function (EF) was mainly based on the synergistic relationship, which mostly occured in the traditional agricultural areas in the west region. The degree of synergy between LF and water conservation function (WCF) first increased and then decreased, with obvious regional differences in the degree of synergy. LF and soil health function (SHF)/ biological diversity function (BDF) was dominated by trade-off relationship, which mostly occured in western saline-alkali land and coastal areas. The performance of multiple EF was the mutual transformation of trade-offs and synergies. The land space of Huanghua could be divided into six types of areas, agricultural production area, urban development core area, urban and rural optimized development area, renovation and improvement area, nature reserve area, and ecological restoration area. There were differences in the dominant mode of land function and optimization strategies in each area. This research could provide scientific refe-rence for clarifying land function relationship and optimizing land spatial development pattern.